Threat or opportunity? Browsing preferences and potential impact of Ammotragus lervia on woody plants of a Mediterranean protected area

Much of the biodiversity in the Mediterranean region depends upon extensive livestock rearing. However, this activity is decreasing, especially in arid environments, where considerable biodiversity loss is expected in the near future. Meanwhile, wild ungulate populations are regaining long lost territories and densities. The question arises as to how far wild ungulates could substitute the ecological role traditionally played by extensive livestock. This study focuses on the effect of an exotic wild ungulate, the aoudad (Ammotragus lervia), on the woody vegetation of a semiarid protected area in Southeast Spain where it was introduced in 1970. Forty-five field surveys provided information on the effect of browsing on 92 woody plant species and on the aoudad's feeding behavior. Small shrubs were the most preferred species and showed, on average, higher levels of browsing damage. However, browsing intensity was low in broadleaved trees and negligible in conifers. Highly preferred and sparse shrub species might be severely affected by medium to high aoudad densities. The aoudad could become an opportunity for arid environments that lack native wild ungulates and traditional livestock grazing, since it could partially fulfill most ecological roles played by livestock. However, it could also become a threat should it become overabundant.